The goal of this research is to identify strategies that could help alleviate the negative social and emotional consequences of facial masking. Facial masking is a motor symptom of PD that results in a decrease in facial expressivity. This reduction is often most noticeable in the expression of positive emotion as it leads to a marked decrease in the production of Duchenne (D) smiles, those that create crow's feet around the eyes. Since D smiles are perceived as expressing genuine happiness, a decrease in the ability to produce spontaneous D smiles is a possible reason why older adults with facial masking are often perceived as depressed, apathetic, and less socially engaged even when experiencing genuine positive affect. At a time in the lifespan when, on average, people are experiencing more happiness, those with facial masking cannot accurately express their true underlying feelings and thus experience stigmatization. The specific aims of the proposed research are to (1) test for a linear decrease in activation of specific facial muscle movements from severe to slight degrees of facial masking, (2) investigate the degree to which production of spontaneously and deliberately produced D smiles positively relates to social engagement in older adults with PD cross- sectionally, and (3) to longitudinally test the degree of change in production of posed and natural D smiles and the predictive capacity of production of D smiles for social engagement over a one year period. The proposed research will use the Facial Action Coding System to gain a comprehensive understanding of the spontaneous parkinsonian face. In addition, a deliberate facial movement task will measure older adults with PD's ability to produce deliberate D smiles and test how this ability, is related to social engagement. This procedure will be repeated at two additional time points in order to understand how change in smile production relates to change in social engagement over time. Together the attainment of these objectives will provide evidence for possible self-management strategies to improve interpersonal functioning and quality of life in older adults with decreased spontaneous expression due to Parkinson's disease or other chronic health conditions related to aging.